The present invention relates to a device for guiding the feed of one or more stamping foils as they enter a platen press.
The invention finds a particularly advantageous application in the field of stamping machines.
It is known practice for texts and/or patterns to be printed by stamping, that is by using pressure to apply colored or metalized film taken from one or more stamping foils, commonly known as metalized foils to a medium in sheet form. In the relevant industry, such a transfer operation is usually performed using a vertical platen press into which the print supports are introduced, sheet by sheet, while the stamping foils are fed continuously.
In a standard platen press, stamping is performed between a fixed platen extending horizontally and a platen mounted to move in a reciprocating vertical movement. Because this type of press is generally automated, conveyer means are provided to bring one sheet at a time between the platens. In practice, the conveyor means usually comprises a series of gripper bars, each of which in turn grasps a sheet at its leading or front edge, before then pulling the sheet between the two platens of the press when the platens have been parted sufficiently.
A stamping foil is itself comprised of a backing foil of polyester type, to which a pigmented layer is secured by a layer of wax. The external face of the pigmented layer is coated with a coat of hot-melt adhesive. Like feeding of the sheets, the feeding of stamping foils to the press is conventionally automated, by a drive system capable of unwinding each of the foils and feeding it along a clearly determined feed path which notably passes through the platen press. In general, such a foil feed system combines a series of diverting bars, which are installed along the entire feed path to guide the progress of the foils, with a number of advance shafts which are positioned downstream of the feed path in order respectively to drive the movement of each of the foils.
In practice, because the feed path of the stamping foils passes through the platen press, a diverting bar is often present in direct proximity to the entrance to the press. Because the position at which that bar is installed governs the passage of the foils between the platens, that bar is usually rigidly secured to a fixed part of the press, generally the upper platen.
This type and placement of a diverting bar does, however, have the disadvantage of being particularly exposed to soiling, while at the same time being intrinsically difficult to access. It therefore proves to be extremely difficult to clean it or perform mechanical interventions on it.
The soiling particularly concerns the metalized or colored particles, particles of adhesive, and also surrounding dust. The diverting bar is intended to be in permanent contact with the stamping foils which have colored or metalized film on one side and adhesive on the other. The diverting bar therefore logically has a tendency to become soiled rapidly.
The lack of accessibility of the diverting bar is essentially due to its being installed in direct proximity to the entry to the platen press, which is a particularly cluttered region of the stamping machine. In this region, it is common to find a locking system of the chassis which supports certain tools of the platen press, a locking system of the gripper bars, a fly, and particularly bulky elements of the gripper bar drive system.
Hence, the technical problem which the present invention attempts to solve is proposing a device for guiding at least one stamping foil at the entrance to a platen press, which device makes it possible to avoid the problems of the prior art by offering substantially better ease of maintenance.